The technique disclosed in this specification relates to an engine reciprocative rotation mechanism including a piston reciprocating in a cylinder, a connecting rod connecting the piston and a crankshaft together, and first and second dynamic vibration absorbers provided to the piston or the connecting rod, and a method for manufacturing such a mechanism.
In general, in an engine mounted in a vehicle such as a motor vehicle, a piston reciprocating in a cylinder is connected to a crankshaft through a connecting rod. Specifically, the piston is connected to a small end of a connecting rod through a piston pin, and the crankshaft is connected to a large end of the connecting rod. Conventionally, various techniques of reducing noise generated during the operation of the engine have been developed.
Japanese Unexamined Patent Publication No. 2015-151877 discloses, in order to solve a problem that a piston, a piston pin, and a small end of a connecting rod which are connected together collectively resonate with respect to a large end of the connecting rod in a combustion stroke of an engine, providing the interior of the piston pin with a dynamic vibration absorber to reduce a resonance vibration level. Japanese Unexamined Patent Publication No. 2015-151877 further discloses, in order to solve a problem of relatively increasing a resonance vibration level in a crankshaft and a cylinder block in a situation where the dynamic vibration absorber is disposed inside the piston pin, disposing not only the dynamic vibration absorber (a first dynamic vibration absorber) for reducing the vibration level by resonance in, e.g., a piston pin, but also a second dynamic vibration absorber having a different resonance frequency from the first dynamic vibration absorber in a through hole of the piston pin to reduce the vibration level by resonance in, e.g., the crankshaft.